In an ideal Dynamics 365 (Dataverse) project, plugin source code lives safely in a version-controlled repository, flows cleanly through Azure DevOps pipelines, and is always recoverable. In reality, many of us inherit environments where that discipline didn’t exist. I recently worked with a customer where: This created a common but uncomfortable challenge in the Dynamics 365 world:How do you maintain, debug, or enhance plugins when the source code is lost? Rewriting everything from scratch was risky and time-consuming. Guessing behavior based on runtime results wasn’t reliable. Fortunately, Dynamics 365 and the .NET ecosystem give us a practical and effective alternative. Using XrmToolBox and JetBrains dotPeek, it is possible to recover readable C# plugin code directly from the deployed assembly. (Though the C# Class code recovered won’t be 100% exact, as the variable names would be different and generic; it is only suitable for close logic, structure & functional recovery) The Practical Solution The approach consists of two main steps: This does not magically restore comments or original formatting, but it does give a working, understandable code that closely reflects the original plugin logic. Tools Used Step 1: Extract the Plugin Assembly from Dataverse 1. Connect to the Environment 2. Load the Assembly Recovery Tool 3. Download the DLL At this point, you have successfully recovered the compiled plugin assembly exactly as it exists in the environment. Step 2: Decompile the DLL Using JetBrains dotPeek 1. Open dotPeek 2. Explore the Decompiled Code dotPeek will: One can now browse through: This is usually more than enough to understand how the plugin works. 3. Export to a Visual Studio Project (Optional but Recommended) One of dotPeek’s most powerful features is Export to Project: This gives you a proper .csproj with class files that you can open, build, and extend. Possibilities with the Recovered Code Once you have the decompiled C# code, several options open up: 1. Rebuild the Plugin Assembly 2. Re-register the Plugin 3. Maintain or Enhance Functionality Important Considerations Key Takeaway Losing plugin source code does not mean losing control of your Dynamics 365 solution. With XrmToolBox’s Assembly Recovery Tool and JetBrains dotPeek, you can: There are chances while working in Dynamics 365 technologies, that a developer might face this situation. Knowing this technique can save days-or weeks-of effort and give your customer confidence that their system remains fully supportable. We hope you found this blog useful, and if you would like to discuss anything, you can reach out to us at transform@cloudfronts.com